The invention relates to a semiconductor component for a sensor, in particular for a pressure sensor or differential pressure sensor, having a semiconductor substrate on which one or more electronic components are formed and connected and at least one side of which is provided with an electrically insulating layer and a metal-containing amorphous protective layer.
Such semiconductor components, in particular for application as a pressure sensor or differential pressure sensor, are known for example from German Utility Model No. DE 297 24 622 U1. They consist of a semiconductor substrate, which is designed to be thin in the region which is to form the later membrane region of the sensor. The actual measurement elements in the form of resistors are also formed in this region and are typically arranged into a measurement bridge and change their resistance characteristics with later application, on account of the membrane extension, which in turn may be used for electronic evaluation as a measure of the prevailing pressure. The silicon substrate, as well as the measurement elements formed thereon, at the upper side and lower side of the substrate, are in each case provided with an insulating layer, typically an oxide layer, which in turn is coated with a corrosion-resistant metal layer, for example a chromium-tantalum layer. This metal layer, with known components, extends at both sides up to the edge, and is interrupted only in the region of the connection contacts. It is designed in an amorphous manner and protects the semiconductor component from contact with a medium whose pressure is measured. This protective metal layer is so thin, that it practically does not prevent the movement of the membrane caused by pressure, but provides a reliable protection.
A semiconductor component designed in such a manner has basically proven its worth. However, with unfavorable process parameters, it does indeed occur that the metal layer does not completely stick to the semiconductor component, which is disadvantageous. Moreover, due to contamination or process instabilities, it may occur that the metal layer is not homogeneous in the relevant region, or comprises defect locations. This may lead, sooner or later, to a defect of such a semiconductor component. Moreover, it has been found, in particular, that if the surface of the semiconductor component is not formed in a completely smooth manner, then defect locations in the metal layer occur particularly frequently where steps or other topographic unevenness are present.